UVa11059

Given a sequence of integers S = {S1, S2, . . . , Sn}, you should determine what is the value of the
maximum positive product involving consecutive terms of S. If you cannot find a positive sequence,
you should consider 0 as the value of the maximum product.

Input
Each test case starts with 1 ≤ N ≤ 18, the number of elements in a sequence. Each element Si
is
an integer such that −10 ≤ Si ≤ 10. Next line will have N integers, representing the value of each
element in the sequence. There is a blank line after each test case. The input is terminated by end of
file (EOF).

Output
For each test case you must print the message: ‘Case #M: The maximum product is P.’, where
M is the number of the test case, starting from 1, and P is the value of the maximum product. After
each test case you must print a blank line.

Sample Input
3
2 4 -3
5
2 5 -1 2 -1

Sample Output
Case #1: The maximum product is 8.
Case #2: The maximum product is 20.

题意：输入n个元素组成的序列S，你需要找出一个乘积最大的连续子序列 。如果这个最大的乘积不是正数，就输出0（表示无解）。 1<=n<=18   -10<=S<=10

输出格式  每输出一组案例就空一行（注意）

程序分析：连续子序列有两个要素：起点和重点。所以只要枚举起点和终点就好。由于每个元素与的最大值不会超过10,且不超过18个元素，最大乘积不会超过10的18次方。所以可以用long long储存（试了一下，用int的话，输出18个10的结果不对，int存不下）

程序代码：

#include <stdio.h>
int a[20];
int main()
{
    int n,N=0,c2=0;
    while(scanf("%d",&n)==1)
    {
        long long c,c2=0;
        ++N;
        for(int i=0; i<n; i++)
            scanf("%d",&a[i]);
        for(int q=0;q<n;q++)
        {
            c=1;
            for(int z=q;z<n;z++)
            {
                c*=a[z];
                if(c>c2)
                    c2=c;
            }
        }
        if(c2<=0)
            printf("Case #%d: The maximum product is 0.

",N);
        else
            printf("Case #%d: The maximum product is %lld.

",N,c2);
    }
    return 0;
}